US Patent 9678327 Endoscope objective lens and endoscope

An endoscope objective lens consists essentially of, in order from the object side, a negative first lens group, a stop, and a positive second lens group. At least one of the first lens group and the second lens includes only one cemented lens which is formed by a positive lens and a negative lens cemented together. The entire system includes a positive single lens. The endoscope objective lens satisfies given condition expressions relating to the focal length of the entire system, the center thickness of the positive single lens, the center thickness of the cemented lens, the distance from the most object-side lens surface to the stop, and the distance from the stop to the most image-side lens surface.